Add a way to use potion and spells before Flee

[lionaneesh]

for example: A mage is at 30% hp and suddenly aggro by 1 more mob. Then it starts to flee and it want to cast FrostNova and Pop a healing potion before starting to navigate. As this will improve the chances of escaping a lot.

[Xian55]

Gooday, its a good idea, and its somewhat easy to incorporate, well at least adding the most basic support to be able to use any KeyActions while the FleeGoal is active.

Added with #645

Here's a snippet which allows you achieve your goal.
its important to keep in mind that the first action called Flee is important to remain as its used for the FleeGoal condition to be executed at all.

"Flee": {
  "Sequence": [
    {
      "Name": "Flee",
      "Requirement": "MobCount > 1" //&& Health% < 50
    },
    {
      "Name": "Frost Nova",
      "Key": 6,
      "Requirement": "InMeleeRange"
    },
    {
      "Name": "HP Potion",
      "Key": 7,
      "Requirement": "Health% < 50"
    },
    {
      "name": "Blink",
      "Key": "F3",
      "Requirement": "!InMeleeRange"
    }
  ]
},

Although Blink may cause issues with the Navigation. Be advised.

[Xian55]

Also added more examples when the FleeGoal could be used in the Readme.md